#import "CaptchaView.h"

#define kRandomColor [UIColor colorWithRed:arc4random() % 256 / 256.0 green:arc4random() % 256 / 256.0 blue:arc4random() % 256 / 256.0 alpha:1.0];

//#define kRandomColor [UIColor grayColor];
#define kLineCount 6
#define kLineWidth 1.0
#define kCharCount 4
#define kFontSize [UIFont systemFontOfSize:arc4random() % 5 + 15]

@implementation CaptchaView
@synthesize changeString,changeArray;

- (instancetype)initWithFrame:(CGRect)frame
{
  if (self = [super initWithFrame:frame]) {

    self.layer.cornerRadius = 5.0; //設(shè)置layer圓角半徑
    self.layer.masksToBounds = YES; //隱藏邊界
    self.backgroundColor = kRandomColor;

    //    [UIColor grayColor]

    //顯示一個隨機驗證碼
    [self changeCaptcha];
  }

  return self;
}
#pragma mark 更換驗證碼,得到更換的驗證碼的字符串
-(void)changeCaptcha
{
  //<一>從字符數(shù)組中隨機抽取相應(yīng)數(shù)量的字符，組成驗證碼字符串
  //數(shù)組中存放的是全部可選的字符，可以是字母，也可以是中文
  self.changeArray = [[NSArray alloc] initWithObjects:@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"A",@"B",@"C",@"D",@"E",@"F",@"G",@"H",@"I",@"J",@"K",@"L",@"M",@"N",@"O",@"P",@"Q",@"R",@"S",@"T",@"U",@"V",@"W",@"X",@"Y",@"Z",@"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",@"i",@"j",@"k",@"l",@"m",@"n",@"o",@"p",@"q",@"r",@"s",@"t",@"u",@"v",@"w",@"x",@"y",@"z",nil];

  //如果能確定最大需要的容量，使用initWithCapacity:來設(shè)置，好處是當(dāng)元素個數(shù)不超過容量時，添加元素不需要重新分配內(nèi)存
  NSMutableString *getStr = [[NSMutableString alloc] initWithCapacity:kCharCount];
  self.changeString = [[NSMutableString alloc] initWithCapacity:kCharCount];

  //隨機從數(shù)組中選取需要個數(shù)的字符，然后拼接為一個字符串
  for(int i = 0; i < kCharCount; i++)
  {
    NSInteger index = arc4random() % ([self.changeArray count] - 1);
    getStr = [self.changeArray objectAtIndex:index];

    self.changeString = (NSMutableString *)[self.changeString stringByAppendingString:getStr];
  }
}

#pragma mark 點擊view時調(diào)用，因為當(dāng)前類自身就是UIView，點擊更換驗證碼可以直接寫到這個方法中，不用再額外添加手勢
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
  //點擊界面，切換驗證碼
  [self changeCaptcha];

  //setNeedsDisplay調(diào)用drawRect方法來實現(xiàn)view的繪制
  [self setNeedsDisplay];
}

#pragma mark 繪制界面（1.UIView初始化后自動調(diào)用； 2.調(diào)用setNeedsDisplay方法時會自動調(diào)用）
- (void)drawRect:(CGRect)rect {
  // 重寫父類方法，首先要調(diào)用父類的方法
  [super drawRect:rect];

  //設(shè)置隨機背景顏色
  self.backgroundColor = kRandomColor;

  //獲得要顯示驗證碼字符串，根據(jù)長度，計算每個字符顯示的大概位置
  NSString *text = [NSString stringWithFormat:@"%@",self.changeString];
  CGSize cSize = [@"S" sizeWithAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:20.0]}];
  int width = rect.size.width / text.length - cSize.width;
  int height = rect.size.height - cSize.height;
  CGPoint point;

  //依次繪制每一個字符,可以設(shè)置顯示的每個字符的字體大小、顏色、樣式等
  float pX, pY;
  for (int i = 0; i < text.length; i++)
  {
    pX = arc4random() % width + rect.size.width / text.length * i;
    pY = arc4random() % height;
    point = CGPointMake(pX, pY);
    unichar c = [text characterAtIndex:i];
    NSString *textC = [NSString stringWithFormat:@"%C", c];

    [textC drawAtPoint:point withAttributes:@{NSFontAttributeName:kFontSize}];
  }

    //調(diào)用drawRect：之前，系統(tǒng)會向棧中壓入一個CGContextRef，調(diào)用UIGraphicsGetCurrentContext()會取棧頂?shù)腃GContextRef
    CGContextRef context = UIGraphicsGetCurrentContext();
    //設(shè)置畫線寬度
    CGContextSetLineWidth(context, kLineWidth);

    //繪制干擾的彩色直線
    for(int i = 0; i < kLineCount; i++)
    {
      //設(shè)置線的隨機顏色
      UIColor *color = kRandomColor;
      CGContextSetStrokeColorWithColor(context, [color CGColor]);
      //設(shè)置線的起點
      pX = arc4random() % (int)rect.size.width;
      pY = arc4random() % (int)rect.size.height;
      CGContextMoveToPoint(context, pX, pY);
      //設(shè)置線終點
      pX = arc4random() % (int)rect.size.width;
      pY = arc4random() % (int)rect.size.height;
      CGContextAddLineToPoint(context, pX, pY);
      //畫線
      CGContextStrokePath(context);
    }
}
@end